The composer Arnold Schoenberg has typically been seen as a radical, imposing figure who loomed over the 20th century -- the pioneer of atonality, the inventor of the 12-tone compositional method, an artist whose music is more often explained, defended and, in many quarters, deplored, than listened to.

It is this view of Schoenberg that the composer Allen Shawn takes on in his fascinating new book, ''Arnold Schoenberg's Journey.'' That composer's works ''have not had a fair chance to be experienced apart from the ideology that surrounds them,'' Mr. Shawn asserts. Not entirely facetiously, Mr. Shawn, who teaches at Bennington College in Vermont, suggests that perhaps Schoenberg's work ''deserves a more superficial treatment than it has hitherto received.''

Though organized chronologically, the book is not a biography, but a collection of elegant and persuasive essays: analytic discussions of single works and vivid accounts of phases and facets of Schoenberg's life, like his stint as a cabaret composer in Berlin in 1901-2. There is even an amusing little essay on the implications for Schoenberg of being short: like Schubert, Mahler and Webern, he was under 5 foot 4.

In part, Mr. Shawn was prompted to write the book by his experiences introducing Schoenberg's works to students, who, knowing little about the composer, often take to him instantly, Mr. Shawn reports. These young movie, theater and rock fans recognize in Schoenberg a powerful, authentic and amazing voice and are intrigued by his unconventional entry into music.

Born in 1874 to a poor family in Vienna (his mother was a pious Orthodox Jew; his father was a shoemaker), Schoenberg took violin lessons at 8 and later taught himself the cello. Any thought of a conservatory was quashed by his father's death when Schoenberg was 16, which compelled him to leave school to work in a bank.

He nonetheless became a compulsive concertgoer and an avid at-home chamber music player, which may account, Mr. Shawn writes, for the lucid texture of even his large orchestral works. That he was largely self-taught as a composer is extraordinary, given the prodigious technique he eventually amassed.

Until he fled the Nazis and emigrated to the United States in 1933, Schoenberg resided alternately in Vienna and Berlin, and Mr. Shawn is insightful about the impact of these different cultural milieus. The progressive artistic climate in Berlin seemed to foster social satire and political commentary. But in Vienna, the city of Freud, ''artists tended to pursue expression that was removed from a political and social context,'' Mr. Shawn writes, and ''art turned inward to the aesthetic, spiritual and psychological realms,'' which bolstered Schoenberg's innate desire to tap the unconscious. Surely his serious experiment with painting between 1906 and 1912 was Schoenberg's attempt to access this inner realm in another way.

Mr. Shawn is at his best discussing the motivations for Schoenberg's exploration of atonality at the beginning of the 20th century. The works that he and his composer colleagues were then writing, Schoenberg observed, though supposedly tonal (that is, moored to the system of major and minor keys), had become so wayward, so unhinged that it was time to admit that music was in crises and figure out what to do. In Schoenberg's gargantuan oratorio ''Gurrelieder'' (1901), ambiguous and wildly anomalous harmonic episodes ''are still being made to fit, sometimes just barely, into conventional tonal logic,'' Mr. Shawn writes. But, he adds, ''just because these harmonies are 'prepared' and eventually 'resolve,' doesn't mean that something crucial hasn't changed in the language.''

Schoenberg had the courage to acknowledge the change. The ''new reality,'' as Mr. Shawn puts is, was that the novel harmonies and vagrant chords had become the ''primary point of interest or even of repose.'' It was the tonal ''resolutions'' and ''preparations'' that increasingly seemed ''only decorative, vestigial remnants of an old musical grammar.''

Schoenberg's quest for a new musical grammar culminated in his formulation of 12-tone theory, and Mr. Shawn traces that quest through brilliant and lucid essays on the major works. Alas, these chapters, filled with musical illustrations and technical terms, are not for general readers.

Still, much of the book is quite accessible, for Mr. Shawn is an engaging writer. Perhaps keeping company with good writers has helped: his wife is the author Jamaica Kincaid, his brother is the writer and actor Wallace Shawn, and his father was William Shawn, the vaunted former editor of The New Yorker. He comes up with disarming analogies to make his points, as when he likens the rapid, intense pace of Schoenberg's composing to that of another visionary, the jazz genius Thelonious Monk, who once complained after a concert, ''I played the wrong wrong notes.''

''Watching Monk playing the piano in the film 'Straight, No Chaser,' one sees the concentration of a composer: the choices rejected, those made, the sense of responsibility, the all-out effort up until the last note to keep pushing further,'' Mr. Shawn writes, ''to find the right wrong notes.''

Mr. Shawn effectively relates Schoenberg's severe yet sometimes fanciful character to his works, theories and polemics. A chronic analyzer of everything, Schoenberg could not help but explain exactly what he did wrong when he muffed a shot in tennis. (While living in Los Angeles, he played quite aggressively with friends like George Gershwin and the Marx Brothers.) He wrote a stunningly original treatise on harmony, but also invented board games, like Coalition Chess, and gadgets, like a design for a musical typewriter.

There is a devastating chapter on the silent feud between Schoenberg and Stravinsky that lasted from 1912 until Schoenberg's death in 1951. It goes without saying, Mr. Shawn comments, that when two artists of this stature ''deride each other's work, a selective deafness is in operation.'' Mr. Shawn also gives a poignant account of Schoenberg's mandatory retirement at 70 from the University of California in 1944. At the time he had young children to support from his second marriage, and a pension of $38 a month.

Again, the only drawback to this fine book is that Mr. Shawn's technical discussions of Schoenberg's works will be lost on many potentially interested readers, including those new listeners he is so heartened to observe responding to this great composer's mesmerizing voice.